This invention relates to an apparatus and method for cleaning a shell-type cooler in situ and cleaning liquid for use therewith and more particularly to an apparatus and method for cleaning a cooler used for cooling turbine lubrication.
In large power generation plants, coolers have heretofore been provided for cooling the lubricating oil for lubricating the bearings of turbines. Such lubricating oils create a hydrodynamic film between the bearing and the shaft of the turbine to maintain a separation between the metal surfaces. Because of friction, the lubricating oil becomes heated as it travels through the lubricating system which includes oil reservoirs and recirculating pumps. The coolers are utilized to keep lubricating oil at temperatures which are within operating limits to protect the bearings, control valves, etc. of turbines and also to prevent deterioration of the lubricating oil due to contamination or degradation. The cooler utilized is in effect a heat exchanger which can be mounted vertically or horizontally and typically is of a shell type which includes a tube bundle, a shell enclosing the tube bundle and a head. The tube bundle serves as a cooling element with cooling water flowing inside of the tubes and lubricating oil flowing in the shell over the outsides of the tubes. The head has channel-type ports that cause the cooling water to pass through all of the tubes of the tube bundle. The shell retains the turbine lubricating oil which flows over the tubes. The tubes are clamped to the shell and are sealed using o-rings to assure that the water and oil do not come into contact with each other. The cooler and the system associated therewith acts as a catch basin for oil contaminants such as varnish deposits and other foreign matter that may effect the efficiency of the cooler. It is therefore necessary to periodically clean the coolers to maintain their efficiency. Various procedures have been utilized in the past to clean coolers. One approach has been to pull the tube bundle from the shell and soak the tube bundle in a vat of chemicals and/or petroleum solvents to remove the contaminants on the outside of the tubes. This generally is undesirable because the chemicals require special handling and are difficult to dispose of properly to meet environmental standards. In addition, removal of the tube bundles from the shell requires special handling to prevent damage to the tube bundles. Also there is the possibility of damage to the shell during the bundle removal. Typically such tube bundles when replaced must be pressure tested. There is therefore a need for a new and improved apparatus and method for cleaning a cooler in situ.
In general, it is an object of the present invention to provide an apparatus and method for cleaning a shell-type cooler in situ and a lubricant for use therewith.
Another object of the invention is to provide an apparatus and method of the above character which does not require removal of the tube bundle from the shell.
Another object of the invention is to provide an apparatus and method of the above character in which the tube bundle and the shell interior can be cleaned without danger of damaging interior parts.
Another object of the invention is to provide an apparatus and method of the above character in which a cooler of either a dual type or a single type can be cleaned.
Another object of the invention is to provide an apparatus and method of the above character in which the cooler is isolated from the reservoir and other hydraulic lines to prevent interference with the cleaning.
Another object of the invention is to provide a cleaning liquid for use with the apparatus and method of the present invention.
Additional objects and features of the invention will appear from the following description in which the preferred embodiment is set forth in detail in conjunction with the accompanying drawings.